RFL-free dipping composition providing high performance for cord fabrics

Abstract

The present invention relates to a dipping material composition for cord fabric which is free of resorcinol and formaldehyde and production methods thereof comprising the steps of adding an acrylic resin containing a carboxylic acid group, adjusting pH value, adding an epoxy resin, adding a blocked polyisocyanate, adding a styrene butadiene latex and adding a styrene butadiene vinylpyridine latex into water, obtaining the dipping material, enabling the synthetic fiber and the rubber used in cord fabric reinforced rubber materials production to be attached to each other by providing an interface between the two said materials. Since the composition is formaldehyde-free, it is not as hazardous for human health as resorcinol-formaldehyde-latex (RFL) based systems and it is also environmentally friendly.

The invention claimed is: 
     
       1. A dipping material composition characterized in that it comprises a functional acrylic polymer resin containing carboxylic acid, epoxy resin, blocked polyisocyanate, styrene-butadiene-latex (SBR) and styrene-butadiene-vinyl-pyridine latexes (VP), wherein in its content the acrylic polymer resin is used in a ratio of 0.5-10% by weight, the epoxy is 2-10% by weight, polyisocyanate is 5-17%, by weight styrene-butadiene latex is 5-17% by weight, styrene-butadiene-vinyl pyridine latex is 50-80% by weight. 
     
     
       2. The dipping material composition of  claim 1 , wherein the acrylic polymer resin is used in a ratio of 1.5-5% by weight. 
     
     
       3. The dipping material composition of  claim 1 , wherein the epoxy is 4.5-7% by weight. 
     
     
       4. The dipping material composition of  claim 1 , wherein the polyisocyanate is 9-14% by weight. 
     
     
       5. The dipping material composition of  claim 1 , wherein the styrene-butadiene latex is 10-13% by weight. 
     
     
       6. The dipping material composition of  claim 1 , wherein the styrene-butadiene-vinyl pyridine latex is 65-75% by weight. 
     
     
       7. The dipping material composition according to  claim 1 , wherein the carboxylic acid is formed with at least one of the monomers selected from acrylic acid, methacrylic acid, itaconic acid, crotonic acid, cinnamic acid and maleic acid. 
     
     
       8. The dipping material composition according to  claim 1 , wherein the carboxylic acid content therein is between 10-100% by mole. 
     
     
       9. The dipping material composition providing of  claim 8 , wherein the carboxylic acid content therein is between 30-70% by mole. 
     
     
       10. The dipping material composition according to  claim 1 , wherein the epoxy resin is water soluble or a water based dispersion. 
     
     
       11. The dipping material composition according to  claim 10 , wherein the epoxy resin is at least one of glycidyl based glycerol, sorbitol epoxy, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylol propane polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, phenol novalac epoxy, cresol novalac epoxy, cresol novalac and bisphenol A. 
     
     
       12. The dipping material composition according to  claim 1 , wherein the blocked polyisocyanate used is either water based blocked polyisocyanates or water based polyurethane prepolymers. 
     
     
       13. The dipping material composition according to  claim 12 , wherein the water based blocked polyisocyanates or water based polyurethane prepolymers is at least one of tetramethylene diisocyanate, hexamethylene disocyanate (1,6-diisocyanatohexane), octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, aromatic isocyanates 2,4- or 2,6-tolylene diisocyanate, tetramethylxylene diisocyanate, p-xylene diisocyanate, 2,4′- or 4-4′-diisocyanatediphenylmethane, 1,3- or 1,4-phenylene diisocyanate and wherein the blocked polyisocyanate is used alone and in the form of a functional group attached to the polymer. 
     
     
       14. The dipping material composition according to  claim 1 , wherein the blocked polyisocyanate is obtained by blocking free isocyanates with at least one of the blocking agents selected from the group consisting of phenol, thiophenol, chlorophenol, cresol, resorcinol, p-sec-butylphenol, p-tert-butylphenol, p-sec-amylphenol, p-octylphenol, p-nonylphenol, tert-butyl alcohol, diphenylamine, dimethylaniline, phthalic imide, δ-valerolactam, ε-caprolactam, malonic acid dialkylester, acetylacetone, acetoacetic acid alkylester, acetoxime, methylethylcetoxime, cyclohexanonoxime, 3-hydroxypyridine and acidic sodium sulfite. 
     
     
       15. The dipping material composition according to  claim 12 , wherein the water based polyurethane prepolymer has a molecular weight of which is in the range of 1000-10000 g/mol. 
     
     
       16. The dipping material composition according to  claim 15 , wherein the water based polyurethane prepolymer has a molecular weight of which is in the range of 1500-3000 g/mol. 
     
     
       17. The dipping material composition according to  claim 1 , wherein at least one of said styrene-butadiene-latex (SBR) or styrene-butadiene-vinyl-pyridine latexes (VP) is selected from the group consisting of vinylpyridine-styrene-butadiene, vinylpyridine-styrene-butadiene modified with carboxylic acid, styrene-butadiene, and styrene-butadiene modified with carboxylic acid. 
     
     
       18. The dipping material composition according to  claim 17 , wherein the butadiene component of the styrene-butadiene-latex (SBR) or styrene-butadiene-vinyl-pyridine latexes (VP) is 1,3-butadiene and 2-methyl-1,3-butadiene. 
     
     
       19. The dipping material composition according to  claim 17 , wherein the styrene component of the styrene-butadiene-latex (SBR) or styrene-butadiene-vinyl-pyridine latexes (VP) is α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene and hydroxymethylstyrene. 
     
     
       20. The dipping material composition according to  claim 17 , wherein the vinyl pyridine is selected from 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine and 5-ethyl-2-vinylpyridine. 
     
     
       21. The dipping material composition according to  claim 17 , wherein the latex has a solid content of between 35-45%. 
     
     
       22. The dipping material composition according to  claim 21 , wherein the ratio of the solid content of styrene-butadiene latex to the solid content of styrene-butadiene-vinylpyridine latex is in the range of 0.05-1 by weight. 
     
     
       23. The dipping material composition according to  claim 22 , wherein the ratio of the solid content of styrene-butadiene latex to the solid content of styrene-butadiene-vinylpyridine latex is in the range of 0.13-0.30 by weight. 
     
     
       24. A method of producing the dipping material composition according to  claim 1 , characterized by the steps of:
 (a) adding acrylic polymer resin containing carboxylic acid into water, 
 (b) adjusting the pH value to 7-12 by adding ammonium, 
 (c) adding epoxy resin, blocked polyisocyanate, styrene-butadiene-latex (SBR) and styrene-butadiene-vinyl-pyridine latexes (VP) at room temperature, and 
 (d) stirring. 
 
     
     
       25. A method of preparing a cord reinforced composite characterized by the steps of:
 (a) preparing cords in determined construction (ply number and twist), 
 (b) treating the prepared cords with the dipping material composition according to  claim 1 , 
 (c) drying the dipped cords at 100-210° C., 
 (d) curing the dried cords at 200-240° C., 
 (e) embedding the cords in an unvulcanized rubber compound, 
 (f) subjecting the unvulcanized rubber compound to a vulcanization process at a temperature of 170° C. under press for about 20 minutes, and 
 (g) obtaining the final composite material reinforced with cord. 
 
     
     
       26. The method according to  claim 25 , wherein the cord is selected from nylon 6.6, nylon 6, polyethylene terephthalate, polyethylene naphthalate, rayon, or aramide.